What causes a plant to wilt or die back to nothing?
I am not having any luck with penstomens, Lobelia cardinalis, delphinum's, milkweed and some species of Asters. They get to a certain height and then I don't see them anymore. I don't see a critter damage. They just disappear, with the exception of milkweed which I can't even get to germinate.
What causes such drastic dieback? I have really good soil.